Dr. Laura Gomez-Consarnau
University of Southern California
Lab Website
Light-harvesting in the surface ocean: the ecological role of proteorhodopsin-based photoheterotrophy
Monday, February 5
11 AM
AHF 153 (Torrey Webb Room)
Abstract: Sunlight drives virtually all life on the Earth’s surface, with about 50% of primary productivity occurring in marine systems. However, before the year 2000, all known phototrophic metabolisms in the ocean were based on chlorophyll-like molecules. This traditional view of phototrophy changed radically with the discovery of marine bacterial proteorhodopsins (PR). Since then, PR genes and transcripts have repeatedly been found in extremely high abundances in all sunlit environments, particularly in the surface ocean. PRs are simple light driven proton pumps that allow microbes to transform light into chemical energy. My lab combines physiology studies, with (meta)-genomics, (meta)-transcriptomics and environmental quantifications to try to understand the role of light on PR-based photoheterotrophy in the ocean. In this talk I will show that the solar energy captured by PR-photoheterotrophy can promote bacterial growth, substrate uptake and survival to starvation under organic matter limitation. Also outside the prokaryotic domains, there’s growing evidence that eukaryotic phytoplankton can produce large amounts of PR in response to nutrient limitation. I will further show the first quantitative field estimates of PR in marine systems, and that this photosystem could absorb as much or more light energy than chlorophyll-a–based photosynthesis. Given the predicted expansion of oligotrophic environments in response to global warming, the importance of PR-photoheterotrophy is expected to increase in the future oceans.
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